Children with positive islet autoantibodies monitored prospectively avoid metabolic decompensation at type 1 diabetes (T1D) diagnosis. However, the effects of early diagnosis and treatment on preservation of insulin secretion and long-term metabolic control are unknown. We compared characteristics of children detected through research screening (Diabetes Autoimmunity Study in the Young [DAISY]) versus community controls at baseline and, in a subset, 6- and 12-month metabolic outcomes.